Concrete block dropped on lorry on M4 in Bridgend
Police officers plan to talk to schoolchildren after a large concrete block was dropped on a lorry on the M4.
The HGV's roof was damaged after the block was thrown from a bridge over the motorway near Sarn Park Services, Bridgend, at 19:55 GMT on Wednesday.
Four more vehicles were damaged after hitting debris resulting from the block falling on to the carriageway.
While there were no injuries, police said someone could have died and the damage could total thousands of pounds.
Insp Rowan Moore said: "We are making some contact with local schools to make sure we educate local youngsters in relation to dangers relating to this type of activity.
"It won't only have an impact on their lives, but it will also an impact on people's lives when they lose family members."